Repairing spinnerets



April 1938. H. P. VERSCHRAGEN 2l15403 REPAIRING SPINNERETSA Filed 0017. 27. 1936 Petented Apr. 26, 1938 PATENT OFFICE REPAIRIN G SPINNEBE'I'S Human Petrus Verschragen, Arnhem, Netherlande, a.ssignor to Amerlcan Enka Oorporntien, Enka, N. C., a corporatlon 01 Delaware Application Claims.

This invention relates to repairing spinnerets employed in the manufacture of a ftificial silk, and more particularly to a method cf protecting the sharp edges surrounding the minute orifices in the spinneret'duringthe repairing steps.

The type of spinneret with which this Invention is particularly concerned is a small, eupshaped die having a base platze perforated with minute oriflces through which a. cellulosic spinning solution is extru ded into a coagulating bath to form filaments. These spinnerets must be constructed of materials which will withstand the severe conditions to which they are normally subjected during the spinning operations. For practical working conditions, spinnerets formed of precious metals such es gold and platinum or their alloys are employed to the best advantage.

These metals are substantially non-oxidizablerable to permit use over lang perlods o1 time without frequent replacement.

Although these precious metaispinnerets are the most suitable for the manufacture of artificial silk, they a.t times, da become damaged due to use over prolonged periods. During the spinning operation, incrustations form around the edges of the orifices thereby decreasing the diameters or often entirely closing the minute openings. This necessitates the removal and replacement of the clogged spinnerets. Moreover, the continuous use of the spinnerets in the spinning operation causes a wearing down of the edges of the openings and distorted places to 0ccur in the bases.

The spinnerets which become impaired through usage were for the most part retu.rned to the manufacturer to be melted and reworked into new spinnerets. This seemecl to be a necessary expense, es in order to recondition the defective spinnerets, a success'ful polishing of the faces of the spinnerets had to be efl'ected. However, the polishing action itself tended to damage the sharp edges of the orifices, which edges were already defective a.s a result of wear and corrosion, thereby increasing the objectionable results.

It is therefore the object 015 the presen't Invention to overcome these difliculties by providing a. method oi depositing a layer cf a base metal, for example, nickel, upon the face 01 the spinneret and upon the inner walls of the minute oriflces, whereby the sharp edges 01 the oriflces a.re protected from the action of the polishlng agent until the damaged portions have been removed.

Additional objects will be apparent from the 1ollowing detailed description when considered October 27, 1936, SGl'lll N0. 107379 In Germany Manch 19, 1936 of nickel sulphate. A nickel platze 2, acting as 'the anode of an el ctroplating assembly, is submerged within the tank and suspended in the; solution by mea.ns of a. pa.ir of insulated arms 3. The upper ends of the arms a.re attached to the plates 4 located an the rim of the tank. One of these arms is provided with a. post 5 for connec'- tion to the positive pole oi' an electric battery (not shown) or Seine other source of electrit: power.

A perforated nlckel sheet 6 is also disposed within the tank and acts es the cathode. The

disposition of this sheet is such that it is nor-' mally Suspended adjacent to the surface of the electro-plating solution and preferably a small distance above the solution. The perforations er openings I within the sheet 6 are adapted to support individual spinnerets 8. These spinnerets are inverted so that thelr bases are below the sur-A face of the electro-plating solution.- A plurality of rods 9 are bent a.t their lower ends to support the nickel sheet 6 and at I;heir upper ends ha.ve hooks III adapted to ansage the rim of the tank. The negative post II may be located on any one of the rods and connected to the electroplating assembly.

In conducting the process the spinnerets are first thoroughly cleaned in a, bichromate su1- phurlc acid bath, rinsed wlth clean water and thereafter positioned within the openings of the nickel sheet acting as the cathode. The height of the electro-plating solution is such that the spinnerets are partlally submerged within the solution. The Current is then turned on whereby the bases of the spinnerets and the walls cf the orifices thereln are electro-plated with nlckel. In order to ins11re that all o1 the oriflces will be compietely fllled with the electro-plating solution, rubber tubes I2 or the 1ike as indicated in F'igure 3 may be fitter! into the spinnerets and the solution dra.wn therethrough by means of suction. This application of suction to the spinnerets also functions to withdraw minute air bubbles whlch are present within the oriflces und which would otherwise inhlblt the free circulation of the electro-platlng solutlon. T0 further gua.ra.ntee the removal o1 the air bubbles the nickel sheet may be removed at lntervals und thoroughly shaken.

The electro-platlng operation l s contlnued until a layer of metal has been deposited to the extent of from 10 to 15 mu. After the completion of the electro-plating, the spinnerets are removed und polished untll the damaged portions have.been r'emoved. It may be necessary to continue such pollshing until substantlally all of the plated metal is removed. The layer o1 metal prevents injury to the sharp edges of the orifices. The layer of metal retained within the oriflces may be easily removed by acid treatment such as d1pping the spinnerets in a streng nitric acid ba.th at approximately 80 C.

It 1s to be understqod that modiflcatlons may be made in the process without departing 1'rom thespirlt und scope of the invention. Foxinstance, a number of dlflerent metals may be employed for electro-deposition on the face o1 the spinnerets und in such ca.ses other metals would be max-e su itable .for the cathode and the anode.

Wha.t I claim ls: l. A method of reconditionlng splnnerets em ployed in the manufacture oi artlflcial silk whlch comprlses partially submerging each of a plurallty of splnnerets in an electrolyte and electroplatlng a layer o1 metal on the bases Lhereol' und around the walls of the oriflces in the bases to thereby protect the sharp edges surroundlng the oriflce during future polishing, polishing am! tratlon cf the electro-plating solutlon into the oriflces by subjecnng the spinnerets to suctlon. polishlng the faces of the spinnerets to eliminate damaged portions und thereafter removing the remainlng metal coating by subjecting the spinnerets to the action of an acid. bath.

HERIVIAN PE'I'RUS VERSCHRAGEN. 

